Icon must support SVG

Because Talend Cloud must relies on SVG whenever possible and not PNG, the framework must lookup SVG first.

The change implies:

1. validate component against a svg presence - for now an error is logged but no exception for backward compatible,
2. Keep the png validation - which implies svg to png logic must be ran before validation,
3. Enrich the server to support SVG and enable to disable it for the Studio.

At the end of the day with the svg2png task this shouldn't break existing components and the studio integration.